The present invention relates to a mail sorting displacement bench, as well as to an insertion flap for guiding letters, more specifically intended for the guidance of letters driven by a belt system, and which have to be individually introduced into each compartment of a rotary drum, before being oriented towards the actual sorting machine.
As a result of the speeds required, the variable dimensions of the letters and the various tolerances, this operation of transferring each individual letter into a rotating drum compartment is far from easy. It is a question of axially introducing into a compartment of a drum rotating at an angular velocity .OMEGA., a letter arriving at speed v, whereby it is motorized between two gripped belts. The letter has a length L and a thickness e. The drum is subdivided into n circular sectors, whose walls form an angle (a) between them. The letters then drop into the compartments moving under the drum. The following difficulties are encountered. The angular velocity .OMEGA. is subject to slow variations and faster variations between the individual sectors. The slow variations or deviations, or the regulating errors can be estimated as .+-.5%. The fast variations are estimated as .+-.10%. In addition, v can be subject to more or less variations, as a function of the care taken in the motorization of the belts. Finally, the letter must be synchronized with the movement of the drum.
The object of the present invention is to solve all these problems of guiding the letter during its insertion into the compartment, as well as the problems linked with controlling the frequency and phase of the arrival and insertion of the letters. It more specifically relates to a displacement or movement bench, having a conveying system, with a natural velocity v, receiving the letters from a destacking magazine and introducing them into moving receptacles. It also relates to an insertion flap, whose function is to increase the time interval available for the insertion of the letters. The invention relates to a displacement bench equipped with such a flap and having a control system linking the operation of the destacker with the operation of the drum.